problems starting C2 327/350hp

i need help getting my vette started.  Battery is fine.
last time it started i turned the key and nothing happened, after a few attempts it fired up without a problem.  This happened twice.  today, nothing, absolutely nothing.  I get power with key turned to auxilary mode, but no juice to the starter when I turn the key.  I'm guessing the problems lies somewhere between the on/off switch, horn relay, or regulator???  The wiring is original and likely the root of the problem?  What tests can I perform and what are common issues with the 327/350 motor.

thanks

bob  

have you the time to take the starter out and apart to clean the commutator???

make sure the brushed are not worn out..

starter repair kits are available at most auto parts stores...

when power is sent down the purple wire to the starter...  the other end of the solenoid winding  is hooked from the S terminal to the bottom post on the solenoid...  this is the post that is hooked to the starter brushes..  

so for the solenoid to pull in.. the circuit has to start at the battery wire that feeds the ignition switch... through the bulk head connector... to the ignition switch, to the neutral safety switch... back through the bulk head connector...  over to the starter solenoid "S " terminal... out the bottom post and into the positive brush.. through the armature through the ground brush to the starter case...  through the starter nose... through the engine block and back to the battery through the ground wire...

this is all before the starter solenoid has built up enough magnetic field to pull the plunger in hard enough to close the contact by depressing the button at the back of the starter solenoid bore...  which pushes the contact ring across both contacts under the solenoid cap sending battery voltage to the armature..

i have measured gm starters... it takes sometimes 50 amps of power to pull the solenoid in hard enough to close the solenoid contacts...

anything that reduces power to the solenoid will cause problems like you describe...    

this is why most newer cars use starter relays to reduce the length of wire between the starter solenoid and the battery...

tests....  do you have a digital volt meter?????    if so you can do voltage drop tests......  
you usually need a long test lead to do these on the starter circuit...

what year C2...  i might be able to post a link of the starting circuit... so you have  a better idea of where to test...

after you inspect the starter...   post what you find... i drop in here almost every day...  post what you find...

there are also problems with burnt terminals in the firewall bulkhead connectors..

loose terminals on the connector of the ignition switch...

you can install a load dropping relay in the starter circuit...

i usually use a starter relay Part Number: CR607,   AZ part number .. fits 71 dodge darts and a lot of others

heres a picture  

http://contentinfo.autozone.com/znetcs/additional-prod-images/en/US/wl2/CR607/3/image/8/

and a different image

http://contentinfo.autozone.com/znetcs/product-info/en/US/wl2/CR607/image/8/

to the 5/16 stud.. run a 10 gauge wire from the starter top post...

from the screw down clamp terminal.. run a 10 gauge wire to the "S" terminal on the solenoid..  

the original S wire goes on the one of the 1/4" push on terminals.. and the other gets a short wire to ground...

this drops the amount of amperage running through the circuit...   makes the car start so fast you won't believe it...

i usually bolt this to one of the heater box studs on other gm cars.... i don't know where you can put it on your vette...

you also might really want to install a short piece of fusible link on the end of the wire that attaches to the top post of the starter...  4 sizes smaller than the wire it is crimped to...   10 gauge wire... 14 gauge fusible link...  12 gauge... 16 gauge fusible link...  

if you don't like it.. its totally removable... just put a new ring terminal on the end of the purple wire

this really does work... if you have the place to install it...  it has been done for years...

if you have a grounded place to mount it... you can also use an earlier version 68 dodge dart application.. that has a solder connection that grounds the coil directly to the case... so you need to make one less wire... but with a car made of  fiberglass.. i just figured it is better to have the extra wire...

there are also other ways to do this...  but this is the least expensive way.. and most of the time the best way...

i also try not to use  cheep wire for the large wires on this..   some electronic stores have higher temp aircraft wire in 10 or 12 gauge... you only need a few feet... pick up 6 or 8 feet... you might only use 2 18 inch runs...  but you cannot make it longer once you cut it...